DEAR DR. DONOHUE: I am a 17-year-old boy, and I have struggled with acne for the past two years. I am not making much progress. What am I doing wrong? I wash my face at least four times a day. I still get pimples. What causes them? – K.K.

ANSWER: Four elements work together to bring on acne. Due to the surge of male hormones at puberty, oil production increases. Simultaneously, skin cells fail to shed normally, and they plug up pores filled to overcapacity with oil. That sets the scene for proliferation of the bacterium propionibacterium, which produces the fourth factor in acne genesis, irritation and inflammation.

Washing your face too often is not helping matters. It only adds to skin irritation. Twice-daily washing is enough, and you should use a mild soap like Dove. Don’t squeeze pimples. You’ll rupture the pore and spread oil and germs into the adjacent skin.

Drugstore shelves are filled with acne medicines. Choose one with benzoyl peroxide. It controls the growth of the propionibacterium germ. One brand name is Clearasil.

You won’t experience an overnight change. It takes six weeks for medicines to have their effect. If, by then, you are not seeing an improvement, you will have to enlist the help of your family doctor, who will put you on prescription medicine.

One group of such medicines are relatives of vitamin A, and they keep pores open. Retin-A, Tazorac and Differin are the names of some of those drugs, which come as ointments, creams, gels and liquids.

Bacteria-killing ointments and creams represent the next step up. And finally, there are oral antibiotics.

Girls with acne are sometimes benefited by birth control pills, which decrease the influence of male hormones. Girls do make male hormones.

DEAR DR. DONOHUE: My fiance has been experiencing erectile dysfunction for two years. He had been under a great deal of stress, and doctors blamed that for the problem. When the stress resolved, nothing changed. My fiance questioned his testosterone level. It came back really low. The doctor said it was dangerous to treat this with testosterone replacement. He is now waiting to see a specialist. I hear ads about treating low testosterone, and it doesn’t seem like a big deal. Is it? – J.R.

ANSWER: The ability to have an erection depends on the interplay of blood vessels, nerves, hormones and the elusive factor called libido. Without unobstructed arteries, sufficient blood cannot flow into the penis for an erection. Without an intact nervous system, signals from the brain cannot cause expansion of arteries for increased blood flow. And without enough testosterone, none of the above takes place. Libido speaks for itself.

A low level of testosterone accounts for less than 10 percent of all cases of erectile dysfunction. When there is a demonstrated deficiency of that hormone, then replacement of it is quite acceptable.

Doctors shy away from overprescribing it because it can be used as an easy out even when hormone levels are normal. Inappropriate use carries with it some potential for danger. Testosterone can cause prostate gland enlargement and all the troubles that such enlargement brings on, like incomplete emptying of the bladder. Testosterone fosters the growth of cancer cells, so growth of incipient cancer could be promoted. Testosterone can worsen congestive heart failure.

When none of the above is present and when there is a deficit of the hormone, then testosterone replacement is indicated and can work.

DEAR DR. DONOHUE: I have blood tests done frequently. The last time I had blood taken, it came out so slowly that the tech pulled out the needle and stuck a vein in the other arm. She said she didn’t know why this happened. Could it be a sign of a circulation problem? – A.B.

ANSWER: It’s not likely a sign of any problem. The needle might have been positioned in such a way that the wall of the vein blocked blood from flowing into it. That’s not a matter of concern.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475.